I'm an Electrical and Computer Engineering Professor at the University of Kentucky. I'm probably best known for things I've done involving Linux PC cluster supercomputing; I built the world's first back in Feb. 1994. The Make world is more likely to have seen my technical report on building a digital fisheye camera for under $20 (or one of the many Instructables that apparently inspired).

Just saw your comment....First try pushing in the stop-down pin. If that works, just treat it as type 3.Odds are that this is a lens designed with a generic mount that is factory adapted to whatever -- in this case, I assume P42 means M42 for Pentax or Praktica. Such lenses often have internal gears to reverse the direction of aperture ring rotation, etc., so it is possible something broke. However, most likely is that there is oil on the blades that is causing too much friction, so the spring that drives the actual blade motion just stretches rather than moving the blades. If so, opening the lens enough to get at the blades from at least one side (and those screws might be the way to do that) will allow you to clean the oil off using many open/close passes gently wiping the blades with...

Just saw your comment....First try pushing in the stop-down pin. If that works, just treat it as type 3.Odds are that this is a lens designed with a generic mount that is factory adapted to whatever -- in this case, I assume P42 means M42 for Pentax or Praktica. Such lenses often have internal gears to reverse the direction of aperture ring rotation, etc., so it is possible something broke. However, most likely is that there is oil on the blades that is causing too much friction, so the spring that drives the actual blade motion just stretches rather than moving the blades. If so, opening the lens enough to get at the blades from at least one side (and those screws might be the way to do that) will allow you to clean the oil off using many open/close passes gently wiping the blades with a Q-tip (perhaps moistened with some solvent). Try not to actually remove the blades for cleaning -- they can be a huge pain to put back.That brings up the other unfortunately possibility: are you sure it has blades? It's not uncommon (especially for Soviet lenses) to be taken apart for cleaning by random folks, and if they couldn't figure-out how to get the blades back in....

It's interesting that we both made bayonet mounts. It used to be everything screwed into one of the many standard filter threads, and my OpenSCAD code targets that, but I have to admit to designing the bayonet version first (because that's the only option on the SX530 HS). Not quite sure when front-of-lens accessory mounting designs became so enamored of bayonets, but it is yet another bit of non-standard interface. Then again, the need for non-standard things is why folk like you and me have 3D printers. ;-)

This is very similar to my instructable, https://www.instructables.com/id/Safely-Shooting-the-Sun-With-the-Canon-PowerShot-S/ , which primarily talks about a 3D-printed solar filter that bayonets to the SX530 HS. However, my instructable also points at my OpenSCAD design for a customizable solar filter that mounts on most lenses via the lens filter thread: https://www.thingiverse.com/thing:2485988

Yup. The problem with the more iffy mounts, such as rubber bands, is that you really don't want any chance the thing will come off. We're shooting with multiple camera arrays so having 'em fall off would be terrible. Worse still, this zoom lens doesn't really leave space for a rubber band when closed, so you'd have a good chance of stripping the lens drive gears if the camera shut down before you removed the filter.

Keep in mind that AstroSolar film isn't intended for direct viewing either. The main advantage is optical quality, which I have to admit is quite good even with some waves in the material. Incidentally, these filters cost us about $1 each -- the only significant cost is the AstroSolar film.

Keep in mind that AstroSolar film isn't intended for direct viewing either. The main advantage is optical quality, which I have to admit is quite good even with some waves in the material.

Teleconverters can help get you a bigger image, but not-very-good ones often decrease resolution nearly as much as they magnify. In any case, you still need the solar filter.Mad Scientist? Nah. I'm an overly creative engineer. ;-)

Cameras don't damage as easily as human eyes do, but a lens focusing the Sun on a spot heats that spot, and it's mostly the heat that causes damage. The sensor itself needs to get pretty hot to be damaged, but a typical "sensor stack" includes a NIR blocking filter, Bayer color filter (the RGB pattern that allows cameras to distinguish color), and coatings that can be far less robust. For that matter, I once tried to clean fungus from an old lens using a semiconductor laser with just a few watts output -- it generally didn't hurt the glass, but even a tiny dot of fungus absorbed enough energy to immediately carbonize the fungus AND melt a dot of glass where the fungus had been; I'd expect similar issues with a stable, focused beam of sunlight on the sensor stack (e.g., cover g...

Cameras don't damage as easily as human eyes do, but a lens focusing the Sun on a spot heats that spot, and it's mostly the heat that causes damage. The sensor itself needs to get pretty hot to be damaged, but a typical "sensor stack" includes a NIR blocking filter, Bayer color filter (the RGB pattern that allows cameras to distinguish color), and coatings that can be far less robust. For that matter, I once tried to clean fungus from an old lens using a semiconductor laser with just a few watts output -- it generally didn't hurt the glass, but even a tiny dot of fungus absorbed enough energy to immediately carbonize the fungus AND melt a dot of glass where the fungus had been; I'd expect similar issues with a stable, focused beam of sunlight on the sensor stack (e.g., cover glass) and even lens elements (with dust particles) over a not-very-long period. There is also the issue that there are materials (e.g., plastics) used along the optical path that have low enough melting points for the focused image of the sun to quickly melt them: http://www.the-digital-picture.com/Help/Flare.aspx

Poor Sun. The only times people want to take its picture are when it just got up, is just going down, or is being photo-bombed by the moon. ;-)

Very similar unit, but it has the X axis on the back rather than the top, so there are five open areas to enclose -- four sides plus the top. It's also a little harder to get a good placement of a webcam inside. The interesting thing is that unit uses a laser cut frame and if they had just not cut holes in four of the five sides, you'd have it almost enclosed....

Interesting. Welding has a much broader spectral profile than laser light, so it's not clear how effective the filters would be. The meaning of "Shade 5" is apparently governed by two formulas: OD = -log T and SN = 1 + (7/3) OD, where T = fraction of light transmitted by the material, OD = optical density, and SN = shade number. If so, Shade 5 is OD=1.7, which sounds feasible for laser light if it blocks the right wavelengths... but does it?

It's not quite just 2 axis. It does speed control on the fan and power control on the laser while talking via USB (well, serial converted to USB) and watching the 6 user buttons. It's rather memory starved -- apparently only 2KB RAM and the 520x520 image to carve goes into EEPROM. Anyway, I agree that it should be more than sufficient hardware to also run a standard G-code interpreter....

There are a lot of this type of mod or open-frame laser engravers out there, but you are talking about a Class 4 (500mW) laser capable of almost instantaneously doing serious permanent damage to eyes, skin, etc. As a minimum, you need to use eyewear to protect from direct or indirect laser light exposure and to never laser materials that emit highly toxic gasses (e.g., PVC and Vinyl emit Chlorine gas). A good overview of the safety issues is in https://www.instructables.com/id/Making-Your-Mini-Laser-Engraver-Safer-and-Better/

I do worry about the balancing of good filtration vs. sufficient airflow. For wood, I think the activated carbon filter is very viable with the tiny fan supplied with the unit; there is a reasonable flow through it with the fan at speed 10 and the burning wood odor is in the "distant campfire" range. I'm less confident I'm at a good filtering level for acrylic, but the little fan can handle a much better filter. I'm still looking at various upgrade options.As for the lens per se, well, it's enough above the workpiece so that the fan has time to divert the smoke pretty well. I've done about 120 engravings so far without any obvious signs of that type of trouble....

The answer should be "No." I suspect it could mark some metals, especially by burning coatings on them, but it isn't intended for that. In fact, it takes fairly high settings on my 1000mW to cleanly engrave the acrylic dice -- power 7/10, dwell time 150ms.

Hi, fellow Kentuckian. :-) I don't think it would do much to copper, if that's what you mean... but I suppose that if it is well tarnished (non-reflective), there's a chance. I'd bet it could drill holes in a circuit board, but that's known to be a bad idea because of the chemicals in the fiberglass resin. Overall, I think a little CNC mill is a better answer for circuit-board fab.

Veroclear is not a consumer-level 3D printable material. The normal extrusion printing process does not produce parts with the same properties. Personally, I have both a MakerGear M2 and a 3040 CNC, so it wouldn't be hard to replicate what you've done. However, my lab doesn't have a CNC (too messy), and for portable making demos I'd want to use either my lab MakerGear M2 or Wanhao I3 (a $400 3D printer which is even more portable). I probably will not get to play with fluidic gates for another month or so, but you've definitely got me thinking about it. ;-)

This is great stuff... but I'm wondering about some substitutions. I think 3D-printed PLA, made fluid-tight with a thin coat of clear polyurethane, should work for an appropriately scaled-up version, but I don't like the membrane fab. Do you think materials like clear plastic food wrap might work instead?